Don't re-use the same iframe element for fixed layouts. Instead destroy and create one every spine item change. This fixes an issue in where MathJax does not reinitialize on spine item document changes.
Don't re-use the same iframe element for fixed layouts.
Instead destroy and create one every spine item change.
This fixes an issue in where MathJax does not reinitialize on spine item document changes.

kivuto/readium-shared-js,NYPL/readium-shared-js,NYPL-Simplified/readium-shared-js,ravn-no/readium-shared-js,readium/readium-shared-js,ravn-no/readium-shared-js,AccessSeoul/readium-shared-js,dariocravero/readium-shared-js,bibliolabs/readium-shared-js,pmstss/readium-shared-js,bibliolabs/readium-shared-js,AccessSeoul/readium-shared-js,NYPL-Simplified/readium-shared-js,kivuto/readium-shared-js,readium/readium-shared-js,NYPL/readium-shared-js,pmstss/readium-shared-js,JoMedia/readium-shared-js,bpyoung/readium-shared-js,bpyoung/readium-shared-js,dariocravero/readium-shared-js